Method for allocating phich and generating reference signal in system using single-user mimo based on multiple codewords when transmitting uplink

ABSTRACT

The present invention relates to a method for generating an uplink reference signal in a system supporting plural uplink-access transmission modes. The method comprises: a step for transmitting the reference signal configuration information about the configuration of a reference signal from a base station to a user device through an uplink grant PDCCH (Physical Downlink Control Channel), and a step for receiving from the user device a sub-frame including the reference signal that is generated based on the reference signal configuration information. The reference signal configuration information is prepared for plural uplink access transmission modes and includes a cyclic shift value for the sequence of the reference signal. The reference signal is supposed to be transmitted to an uplink, and the user device is set up to be operated in the uplink-access transmission mode that corresponding to the reference signal configuration information.

This application is a continuation of, and claims priority to, U.S.application Ser. No. 13/055,390, filed Apr. 5, 2011, which is a NationalStage Entry of International Application No. PCT/KR2009/004065, filedJul. 22, 2009, and claims the benefit of U.S. Provisional ApplicationNo. 61/082, 827, filed Jul. 22, 2008 and U.S. Provisional ApplicationNo. 61/157,525, filed Mar. 4, 2009, all of which are hereby incorporatedby reference in their entirety herein.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a mobile communication technology andan uplink transmission control method, and more particularly, to amethod for allocating a Physical Hybrid Automatic Repeat RequestIndicator Channel (PHICH) and generating a reference signal in a systemusing Single-User Multiple Input Multiple Output (SU-MIMO) based onmultiple codewords upon uplink transmission.

Discussion of the Related Art

In a mobile communication system, a user equipment (UE) may receiveinformation from a base station (BS) in downlink and transmit,information in uplink. The information transmitted or received by the UEincludes data and a variety of control information, and a physicalchannel varies according to the type of information transmitted orreceived by the UE.

FIG. 1 is a view showing physical channels used for a 3^(rd) aGeneration Partnership Project (3GPP) Long Term Evolution (LTE) system,which is an example of a mobile communication system, and a generalsignal transmission method using the same.

When a UE is powered on or when the UE newly enters a cell, the UEperforms an initial cell search operation such as synchronization with aBS in step S101. In order to perform the initial cell search, the UE mayreceive a Primary Synchronization Channel (P-SCH) and a SecondarySynchronization Channel (S-SCH) from the BS so as to performsynchronization with the BS, and acquire information such as a cell ID.Thereafter, the UE may receive a physical broadcast channel from the BSand acquire broadcast Downlink Reference signal (DL RS) in the initialcell search step and confirm a downlink channel state.

The UE, upon completes the initial cell search, may receive a PhysicalDownlink Control Channel (PDCCH) and a Physical Downlink Shared Channel(PDSCH) corresponding to the PDCCH, and acquire more detailed systeminformation in step S102.

Meanwhile, if the UE does not complete access to the BS, the UE mayperform a random access procedure in steps S103 to S106, in order tocomplete access to the BS. In order to perform a random accessprocedure, the UE may transmit a feature sequence via a Physical RandomAccess Channel (PRACH) as a preamble (S103), and may receive a responsemessage to the random access procedure via the PDCCH and the PDSCHcorresponding thereto (S104). In contention-based random access, exceptfor handover, a contention resolution procedure including transmissionof an additional PRACH (S105) and reception of the PDCCH and the PDSCHcorresponding thereto (S106) may be performed,

The UE, having performed the above-described procedure, may then receivethe PDCCH/PDSCH (S107) and transmit a Physical Uplink Shared Channel(PUSCH)/Physical Uplink Control Channel (PUCCH) (S108), as a generaluplink/downlink signal transmission procedure.

FIG. 2 is a view explaining a signal processing procedure for enabling aUE to transmit an uplink signal.

In order to transmit the uplink signal, a scrambling module 210 of theUE may scramble a transmitted signal using a UE-specific scramblingsignal. The scrambled signal is input to a modulation mapper 220 so asto be modulated into complex symbols using Binary Phase Shift Keying(BPSK), Quadrature Phase Shift Keying (QPSK) or 16-Quadrature amplitudemodulation (QAM) according to the kind of the transmitted signal and/orthe channel state. Thereafter, the modulated complex symbols areprocessed by a transform precoder 230, and the processed complex symbolsare input to a resource element mapper 240. The resource element mapper240 may map the complex symbols to time-frequency resource elements usedfor actual transmission. The signal processed as described above may betransmitted to a BS via an SC-FDMA signal generator 250 and an antenna.

FIG. 3 is a view explaining a signal processing procedure for enabling aBS to transmit a downlink signal.

In the 3 GPP LTE system, the BS may transmit one or more codewords indownlink. Accordingly, one or more codewords may be processed byscrambling modules 301 and modulation mappers 302 to configure complexsymbols, similar to the uplink transmission of FIG. 2. Thereafter, thecomplex symbols are mapped to a plurality of layers by a layer mapper303, and each layer may be multiplied by a predetermined precedingmatrix, which is selected according to the channel state, by a precodingmodule 304 and may be allocated to each transmission antenna. Theprocessed signals which will respectively be transmitted via antennasmay be mapped to time-frequency resource elements used for transmissionby resource element mappers 305, and may respectively be transmitted viaOFDM signal generators 306 and antennas.

In a mobile communication system, in a case where a UE transmits asignal in uplink, a Peak-to-Average Ratio may be more problematic thanthe case where a BS transmits a signal in downlink. Accordingly, asdescribed above with reference to FIGS. 2 and 3, downlink signaltransmission uses an OFDMA scheme, while uplink signal transmission usesan SC-FDMA scheme.

FIG. 4 is a diagram explaining an SC-FDMA scheme for uplink signaltransmission and an OFDMA scheme for downlink signal transmission in amobile communication system.

A UE for uplink signal transmission and a BS for downlink signaltransmission are identical in that a serial-to-parallel converter 401, asubcarrier mapper 403, an M-point Inverse Discrete Fourier Transform(IDFT) (or IFFT) module 404 and a Cyclic Prefix (CP) adding module 406are included.

The UE for transmitting a signal using an SC-FDMA scheme furtherincludes a parallel-to-serial converter 405 and an N-point DFT module402. The N-point DFT module 402 performs mapping to contiguous inputpoints in an input unit of TDFT and partially offsets an TDFT (or TFFT)process influence of the M-point IDFT (or IFFT) module 404 such that thetransmitted signal has a single carrier property.

A channel for transmitting ACKnowledgement (ACK)/NegativeACKnowledgement (NACK) for uplink data transmission (Physical UplinkShared CHannel (PUSCH)) in downlink is referred to as a Physical HybridAutomatic Repeat Request Indicator CHannel (PHICH) in a 3GPP LTE system.FIG. 5 is a diagram illustrating a process of transmitting a PHICH in a3GPP LTE system.

Since an LTE system does not use SU-MIMO in uplink, only 1-bit ACK/NACKfor PUSCH transmission of one UE, that is, a single data stream orcodeword, is transmitted through a PHICH. The 1-bit ACK/NACK is encodedinto 3 bits using repetition coding with a code rate of 1/3 (step 501),and three modulation symbols are generated using Binary Phase ShiftKeying (BPSK) (step 502). The modulation symbols are spread using aSpreading Factor (SF) of 4 in the case of normal cyclic prefix and arespread using an SF of 2 in the case of extended cyclic prefix (step503). The number of orthogonal sequences used for spreading be comesSF*2 in terms of In-phase/Quadrature (I/Q) multiplexing concept.Accordingly, SF*2 PHICHs spire ad using SF*2 orthogonal sequences aredefined as one PHICH group and PHICH groups located in a certainsubframe are layer-mapped (step 504), precoded, resource-mapped (step505), and then transmitted.

In a method for allocating downlink PHICH channel resources of a cell,or a BS or a relay node to uplink data transmission of certain userequipments or relay nodes, using a computation process using a lowestPhysical Resource Block (PRB) index of one or more PRBs used fortransmission of a PDSCH and a cyclic shift value set as resources for aDemodulation Reference Signal (DM-RS) used for the channel transmission,a PHICH group index used for transmission out of all PHICH groups and aPHICH channel index within the PHICH group are derived, and PHICHchannels which will be transmitted to the certain UEs or relay nodes areallocated using these indexes. A MIMO scheme may remarkably increasesystem capacity by simultaneously and spatially transmitting severaldata streams (or codewords) using two or more transmission and receptionantennas at a BS and a terminal and may obtain transmit diversity gainor beamforming gain using several transmission antennas. In a transmitdiversity scheme, since the same data information is transmitted throughseveral transmission antennas, it is possible to perform datatransmission with high reliability in a channel state which is rapidlychanged with time and to perform data transmission without feedbackinformation associated with a channel. Beamforming is used to increase aSignal to interference plus Noise Ratio (SINR) of a receiver by applyingrespective adequate weights to several transmission antennas. Ingeneral, in a Frequency Division Duplexing (FDD) system, since uplinkand downlink channels are independent, high reliability channelinformation is necessary to obtain appropriate beamforming gain.Accordingly, separate feedback is received and used from the receiver.

FIG. 6 is a diagram illustrating Spatial Multiplexing (SM) and SpatialDivision Multiple Access (SDMA). SM for a single user is referred to asSM or SU-MIMO. Channel capacity of a MIMO system increases in proportionto a minimum value among the numbers of transmission/reception antennas.SM for multiple users is referred to as Spatial Division Multiple Access(SDMA) or Multi-User MIMO (MU-MIMO).

When using the MIMO scheme, there are a Single Codeword (SCW) scheme forsimultaneously transmitting N data streams using one channel encodingblock and a Multiple Codeword (MCW) scheme for transmitting N datastreams using M (M is always equal to or less than N) channel encodingblocks. Each channel encoding block generates an independent codewordand each codeword is designed for independent error detection.

FIG. 7 is a diagram showing the structure of a transmitter of a MIMOsystem using a MCW scheme. In detail, M data packets are subjected toencoding (e.g., turbo encoding of FIG. 7) and modulation (e.g., QAMmodulation of FIG. 7) so as to generate M codewords, and each codewordhas an independent HARQ process block. The M modulated data symbols aresimultaneously encoded in a MIMO stage according to a multi-antennascheme and are transmitted through respective physical antennas.Thereafter, a receiver feeds back a multi-antenna channel state aschannel quality information so as to control an SM rate, a coding rateand a modulation scheme. In this case, additional control information isnecessary.

A mapping relationship between codewords and physical antennas has acertain format.

FIG. 8 is a diagram showing an example of a mapping relationship betweencodewords and physical antennas. Specifically, FIG. 8 showscodeword-to-layer mapping for SM rate in downlink (DL) of 3GPP TS36.211. As shown in FIG. 8, if SM rate (that is, rank) is 1, onecodeword is mapped to one layer, data of one layer is encoded using apreceding scheme so as to be transmitted through four transmissionantennas. If SM rate is 2, two codewords are mapped to two layers andare mapped to four antennas by a precoder.

If SM rate is 3, one of two codewords is mapped to two layers by aserial-parallel (S/P) converter, two codewords are mapped to threelayers and is mapped to four antennas by a precoder. If an SM rate is 4,two codewords are mapped to two layers by an S/P converter and a totalof four layers is mapped to four antennas by a precoder. That is, in thecase of a BS having four transmission antennas, a maximum of four layersmay be used and four independent codewords may be used. However, in FIG.8, the number of codewords is a maximum of two. Accordingly, in thesystem shown in FIG. 8, if each codeword CW has an independent HARQprocess, a maximum of two independent HARQ processes may be used.

Currently, in the LTE system, on the assumption that a single RF and apower amplifier chain are used in PUSCH transmission, since channelassignment of a downlink PHICH to a PUSCH is designed based on 1-bitACK/NACK per UE, there is a need for improvement in channel capacity andassignment method in consideration of SU-MIMO based on multiplecodewords in PUSCH transmission.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a method forallocating a Physical Hybrid Automatic Repeat Request Indicator CHannel(PHICH) and generating a reference signal in a system using Single-UserMultiple Input Multiple Output (SU-MIMO) based on multiple code wordsupon uplink transmission that substantially obviates one or moreproblems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a method fortransmitting a downlink PHICH of control information for applying a MIMOscheme based on multiple access schemes other than SingleCarrier-Frequency Division Multiple Access (SC-FDMA) in uplink datatransmission and methods for defining and representing controlinformation transmitted in a state of being included in an uplink grantPDCCH including transmission information specified by a cell, a basestation or a relay node in downlink, which includes cyclic shift asresources of Demodulation Reference Signals (DM-RSs) divided on a perantenna (physical antenna or virtual antenna) or transmission layerbasis upon uplink transmission.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, amethod of generating an uplink reference signal in a Single UserMultiple Input Multiple Output (SU-MIMO) system for transmitting one ormore codewords in uplink includes, transmitting, at a base station,reference signal configuration information indicating the configurationof reference signals to be transmitted in uplink to a user equipmentthrough a uplink grant Physical Downlink Control Channel (PDCCH),wherein the user equipment is set to operate according to an uplinkaccess mode corresponding to the information and receiving a subframeincluding the reference signals generated based on the reference signalconfiguration information from the user equipment. The reference signalconfiguration information includes cyclic shift values of sequences ofthe reference signals.

The reference signal configuration information may include informationabout cyclic shifts of N (N≦M) reference signals among all M referencesignals to be transmitted in uplink, and the information includes cyclicshift index of a reference signal used as a criterion among the Nreference signals and offset information for determining cyclic shiftindexes of remaining N−1 reference signals.

The value M may be determined according to a number of physicaltransmission antennas, physical transmission antennas or transmissionlayers of a subframe configured in the user equipment.

The reference signal configuration information may include cyclic shiftindexes of N (N≦M) reference signals among all M reference signals to betransmitted in uplink,

The N reference signals may be Constant Amplitude Zero Autocorrelation(CAZAC) reference signals.

The N reference signals of the M reference signals may toe inserted atpredetermined symbol positions of a time domain and are subjected to aDiscrete Fourier Transform (DFT) process.

The N reference signals of the M reference signals are directly mappedto sample points corresponding to an allocated frequency transmissionband at an input end of Inverse Discrete Fourier Transform (IDFT) orInverse Fast Fourier Transform (IFFT).

In another aspect of the present invention, a method of allocating aPhysical Hybrid Automatic Repeat Request Indicator Channel. (PHICH) fortransmitting ACKnowledgement/Negative ACKnowledgement (ACK/NACK) withrespect to each transmitted codeword in a Single-User Multiple InputMultiple Output. (SU-MIMO) system for transmitting one or more codewordsin uplink includes determining a number of PHICH groups, and determininga PHICH. group index and an orthogonal sequence index, within the PHICHgroup using the number of PHICH groups. The number of PHICH groups isdetermined using a maximum number of codewords upon uplink transmission.

The PHICH group index and the orthogonal sequence index within the PHICHgroup may be determined using a function for providing a unique offsetvalue of each codeword.

It is to toe understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is a view showing physical channels used for a 3^(rd) GenerationPartnership Project (3GPP) Long Term Evolution (LTE) system, which is anexample of a mobile communication system, and a general signaltransmission method using the same;

FIG. 2 is a view explaining a signal processing procedure in which aUser Equipment (UE) transmits an uplink signal;

FIG. 3 is a view explaining a signal processing procedure in which aBase Station (BS) transmits a downlink signal;

FIG. 4 is a diagram explaining an SC-FDMA scheme for uplink signaltransmission and an OFDMA scheme for downlink signal transmission in amobile communication system;

FIG. 5 is a diagram a process of transmitting a PHICH in a 3GPP LTEsystem;

FIG. 6 is a diagram illustrating Spatial Multiplexing (SM) and SpatialDivision Multiple Access (SDMA);

FIG. 7 is a diagram showing the structure of a transmitter of a MIMOsystem, utilizing an MCW scheme;

FIG. 8 is a diagram showing an example of a mapping relationship betweencodewords and physical antennas;

FIG. 9 is a diagram showing a signal processing method in which DFTprocess output samples are mapped to a single carrier in clusteredSC-FDMA;

FIG. 10 is a diagram illustrating PHICH transmission according to anembodiment of the present invention;

FIG. 11 is a block diagram showing the configuration of a device whichis applicable to a UE and a BS and can perform the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the embodiments of the present invention will be describedin detail with reference to the accompanying drawings so as to be easilyimplemented by those skilled in the art. However, the present inventionmay be variously implemented and is not limited to the embodimentsdescribed herein. In the drawings, in order to clearly describe thepresent invention, portions which are not related to the description ofthe present invention will be omitted and similar portions are denotedby similar reference numerals throughout the specification.

Throughout the specification, when a certain portion “includes” acertain component, this does not mea that other components are excludedand o truer components may be included otherwise noted. The terms“unit”, “-or/er” and “module” as used in the specification indicate aunit for processing at least one function or operation, which may beimplemented by hardware, software or a combination thereof.

In an LTE-Advanced (LTE-A) system, clustered SC-FDMA (or DFT-s-OFDMA(DFT spread OFDMA) ) may be applied to conventional SC-FDMA as an uplinkmultiple access scheme added to an SC-FDMA scheme. FIG. 9 is a diagramshowing a signal processing method in which DFT process output samplesare mapped to a single carrier in a clustered SC-FDMA scheme. As shownin FIG. 9, the clustered SC-FDMA scheme is different from the SC-FDMAscheme in that, N-point samples of an output unit of an N-point DFTmodule are divided into clusters, that is, L sample groups, and thesample groups are separately mapped to an M-point IDFT (or IFFT) inputunit. To this end, a Cubic Metric (CM) or a Peak, to Average Power Ratio(PAPR) of a transmitted signal is increased, but is remarkably less thanthat of the OFDMA scheme. In addition, uplink scheduling flexibility canbe increased and an uplink transfer rate can be increased. In uplink ofthe LTE- A system, a certain user equipment, may adaptively select anyone of the SC-FDMA scheme and the clustered SC-FDMA scheme using acertain method, depending on whether there is room for transmit power ascompared with maximum transmit power, thereby performing uplinktransmission.

Accordingly, the system described in the present invention may supportan uplink multiple access scheme. Hereinafter, the present inventionwill be described on the assumption that, a clustered SC-FDMA scheme isused as an uplink multiple access scheme applied to the SC-FDMA scheme.

In the present invention, a method of designing an ACK/NACK channel(hereinafter, referred to as a Physical HARQ Indication Channel (PHICH))transmitted in downlink in an uplink multiple codeword based SU-MIMO(hereinafter, referred to as MCW SU-MIMO) system and a method ofallocating a PHICH index from an uplink data channel on the channel areproposed. In addition, methods of defining and representing controlinformation in a Downlink Control Information (DCI) format on an uplinkgrant PDCCH necessary for allocating a PHICH and specifying a detailedtransmission scheme of the MCW SU-MIMO scheme are proposed.

First, in the uplink MCW SU-MIMO system, a method of transmitting asingle ACK/NACK for multiple codewords and a method of transmitting anACK/NACK for each of multiple codewords may be considered. The contentof the above-proposed methods may vary according to these two methods.Accordingly, the above-proposed methods will be described separately.

1. Method of Transmitting Single ACK/NACK in Uplink MCW SU-MIMO

Hereinafter, on the assumption that a single ACK/NACK is transmitted inUL MCW SU-MIMO, a HARQ process indication method, a DM-RS cyclic shiftindex indication method, and a method of constructing MCS indicationcontent of n codewords will be described.

In certain uplink data transmission situations, if MCW SU-MIMO is used,HARQ processes corresponding in number to the number of codewords may beactivated in transmission using n (1≦n≦2 or 1≦n≦4) codewords accordingto a codeword-to-layer mapping rule on a per rank basis. However, tothis end, as new technical matters of the conventional LTE standard aregenerated due to n ACKs/NACKs and the HARQ processing indication on anuplink grant channel or increase in the number of HARQ processes fromthe viewpoint of UE, forward and backward compatibility between the LTEsystem and the LTE-A system may become complicated.

FIG. 10 is a diagram illustrating PHICH transmission according to anembodiment of the present invention. In order to solve the aboveproblem, the present invention proposes a method of receiving codewordsfrom a certain UE using MCW SU-MIMO, performing error detection using aCRC on a per codeword basis, utilizing the codewords in SuccessiveInterference Cancellation (SIC) decoding, and transmitting one piece ofACK/NACK information for all n codewords through a downlink PHICH forthe purpose of maintaining a single ACK/NACK implemented in the LTEsystem, a single HARQ on an uplink grant PDCCH, and the number of HARQprocesses in the conventional UE uplink transmission.

The ACK/NACK information may be generated using a certain methodaccording to a specific purpose. For example, ACK may be generated -whenerrors are not detected in all n codewords and, otherwise, NACK may begenerated. Thus, one HARQ process is set with respect to all ncodewords. To this end, variations in the PHICH channel design, channelindex allocation method and the uplink. HARQ process operation in theconventional LTE system may be significantly restricted. In anembodiment associated with the proposal of the present, invention, ifthe number of HARQ processes allocated to a certain UE, in certaincarriers of the system is 8 for each of codewords used for transmission,that is, transport blocks, information which may be considered withrespect to the contents of the UL grant channel for specifying ULSU-MIMO transmission and methods supporting UL SU-MIMO in associationwith the information will be proposed as follows.

(1) HARQ Process Indication

This is a field indicating a single HARQ process with respect to ncodewords. In the case of MCW SU-MIMO, as proposed in the presentinvention, if one HARQ process is performed with respect to n codewords,one of process indexes 0 to 7 is allocated. Even, in the case where aHARQ process is individually allocated to each codeword, if a HARQ indexfor a certain reference codeword is specified while being represented by3 bits, the HARQ pr o cresses for the other n−1 codewords areautomatically calculated based on a fixed, offset.

In this case, as described in the present invention, when one piece ofACK/NACK information is transmitted to a UE in downlink, an emptyphenomenon is not generated in a higher layer buffer of the UE due toindependent allocation of ACK/NACK to each codeword. Thus, in a state inwhich a rank greater than 1 is set in MCW SU-MIMO, null transmission ofa certain codeword is not considered. Even when overriding a lower rank(causing single codeword transmission of a rank 1) in a higher rankstate of an eNB (evolved Node B), if one HARQ process is allocated to ncodewords, since indication for specifying a separate codeword is notrequired, errors are not generated due to allocation of 3 bits. The term“overriding” as used in the present invention means that a cell, a basestation or a relay node informs a UE of a rank value indicating anuplink (channel Estate to be applied when a UE transmits a PUSCH usingMCW SU-MIMO. If one ACK/NACK is used with respect to n codewords andindividual HARQ processes are allocated, additional bits indicating thecodewords may be added to the 3-bit HARQ process indication field or maybe defined as a separate explicit codeword indication field. Inassociation with the HARQ process, a New Data Indicator (NDI) may besignaled along with an uplink grant PDCCH. Even when one HARQ process isdefined and signaled, the NDI may be individually set on a per codewordbasis. In sortie cases, since one HARQ process is defined, one NDI maybe defined and signaled as an uplink grant PDCCH.

(2) Method of Indicating Cyclic Shift Index Demodulation-ReferenceSignal (DM-RS)

A method of indicating a cyclic shift index of a. DM-RS on an uplinkchannel will be divided into three cases as follows.

1) First Case

In the first case, in the implementation of the conventional UL SU-MIMO,there is a need for RSs for providing channel estimation fordemodulation and decoding of P (p≦M) reception data streams according toa transmission (Tx) antenna/layer configuration of a UE, which isdefined by m (for example, m may be 2 or 4, 1 or 2, or 3 or 4)representing the number of transmission antennas (virtual antennas orphysical antennas) or the number of virtual-antennas or the number oftransmission layers. At this time, q (q≦p) RSs among the P RSs may bespecified as the cyclic-shift version of the QPSK-basedcomputer-generated sequence of a low correlation property of the case of1 RB/2 RB or the CAZAC base sequence having the length of a region fordata, transmission on frequency subcarriers in certain OFDM, SC-FDMA orclustered SC-FDMA symbols (as TDM, one OFDM, SC-FDMA or clusteredSC-FDMA symbol may be specified or a plurality of OFDM, SC-FDMA orclustered SC-FDMA symbols may be specified, for RS transmission).

RS indexes, which are used as a criterion for indicating the q usedcyclic shift indexes, may be 3 bits ling. As the remaining q−1 cyclicshift indexes are automatically specified using an offset, which isvariably specified according to system circumstances by an arbitraryrule, a fixed offset or a fixed selection rule, it is possible tominimize overhead when the UE signals the used cyclic shift indexes.

2) Second Case

In the second case, as described in the first case, a combination ofcyclic shifts for the remaining q−1 RSs different from a cyclic shiftindex for a RS which is used as a criterion for signaling cyclic shiftindexes for q RSs may be specified or cyclic shift indexes for q RSs maybe specified as 3−α (0<α<3*(q−1)) bits using a certain informationcompression rule. For example, α may be defined as a bit value of a sumof all or part of q−1 RS sequences of values (values less than 3 bits)representing a difference between the indexes for the RSs and the cyclicshift index for the RS which is used as the criterion.

3) Third Case

In the third case, as described in the first case, cyclic shifts for qRSs are explicitly specified on the UL grant channel with respect to qRSs. In this case, the size of the RS cyclic shift field in the controlinformation payload of the UL channel may be 3*q if the bit size of theindividual cyclic shift field is 3 bits.

If p and q are the same in the first cases, RSs of CAZAC sequence of adata band in one or more OFDM, SC-FDMA or clustered SC-FDMA symbols areused as all RSs for all antennas. In the present invention, it isassumed that the antenna includes a virtual antenna, a physical antennaand a transmission layer.

If p and q are different in the first case, as the number of cyclicshifts which can be provided such that the CAZAC RS sequencestransmitted through certain OFDM, SC-FDMA or clustered SC-FDMA symbolsare orthogonal, in a state in which the cyclic shifts for p RSs are notsufficient to enable allocation of one OFDM, SC-FDMA or clusteredSC-FDMA symbol to each slot, OFDM, SC-FDMA or clustered SC-FDMA symbolsfor transmitting a plurality of RS sequences are allocated as in thefirst case and the additional CAZAC RS sequences may be continuouslyallocated. However, since such an allocation scheme directlydeteriorates UL throughput, heterogeneous RSs having low overhead, whichare generated using different methods, are used along with the q CAZACRSs. The number of heterogeneous RSs is set to p-q which is equal to orgreater than 0. At this time, for entire overhead adjustment, q may be0.

As an embodiment of the design of the RS different from the conventionalTDM (OFDM, SC-FDMA or clustered SC-FDMA symbols)-CDM (CAZAC) sequences,in the case of using SC-FDMA or clustered SC-FDMA, a scheme forinserting RSs into a time sample region within arbitrary transmissionsymbols or r (r≧1) predetermined time domain symbol positions at aprevious stage of the DFT or a next stage of the IDFT (or IFFT) may beconsidered.

The RSs inserted into the time domain at the previous stags of the DFTare subjected to spread spectrum spreading to all subcarriers of thefrequency domain within the DFT region through DFT, are subjected toIFFT, are transmitted to a receiver through a channel, and are subjectedto FFT and IFFT in the receiver, thereby extracting channel informationof the antenna on a band for transmitting data from r RSs of the symbolpositions.

A scheme for directly mapping RS sequences to a frequency domain withoutperforming DFT and performing IFFT with respect to the mapped RSsequences and a scheme for directly mapping RS sequences to an OFDM,SC-FDMA or clustered SC-FDMA symbol region on a next stage of IFFT maybe applied. The OFDM, SC-FDMA or clustered SC-FDMA symbol region may bethe entire OFDM, SC-FDMA or clustered SC-FDMA symbol region or a partialtime sample region of the OFDM, SC-FDMA or clustered SC-FDMA symbols. Inthe case where RSs are inserted into OFDM, SC-FDMA or clustered SC-FDMAsymbols for transmitting data, the fixed positions in the OFDM, SC-FDMAor clustered SC-FDMA symbols may be specified and the RSs are insertedat the fixed positions or the RSs may be inserted at positions generatedfrom resource block indexes and/or cell IDs according to a certain rule.In the case where overhead of additional RSs is added, from theviewpoint of data and multiplexing, resources to which RSs will bemapped may be secured using puncturing of symbols for transmitting dataor rate matching.

The UL RS design scheme is applicable not only to the UL SU-MIMO schemebut also to non-spatial multiplexing schemes. In the case of DM-RS,under situation that DM-RS transmission OFDM, SC-FDMA or clusteredSC-FDMA symbols designed based on the conventional TDM-CDM are present,the UL-RS design scheme may be additionally defined in different OFDM,SC-FDMA or clustered SC-FDMA symbols. Alternatively, the UL-RS designscheme may be applied to replace the scheme designating DM-RStransmission OFDM, SC-FDMA or clustered SC-FDMA symbols designed basedon the conventional TDM-CDM. The UL RS design scheme is applicable tonot only the DM-RS but also the SRS.

If the OFDM, SC-FDMA or clustered SC-FDMA scheme is applied to ULtransmission, a pattern in which RSs are inserted at fixed frequencysubcarrier positions within resource blocks in resource block units maybe defined. Such a pattern may be cell-specifically defined by a certainfunction or rule using a cell ID as an input signal. The resource blockincludes both a virtual resource block and a physical resource block.Accordingly, RSs may be inserted upon symbol mapping before IFFT inputof the transmitter. If RSs are inserted into one or more OFDM, SC-FDMAor clustered SC-FDMA symbols for transmitting data, the RSs may beinserted into fixed positions or positions generated from a resourceblock index and/or cell ID according to a certain rule. At this time,resources to which RSs will be mapped may be secured using puncturing ofsymbols for transmitting data or rate matching.

In a certain system, with respect to p-q RSs among p RSs, in anenvironment in which an RS transmission scheme different from theconventional TDM-based CAZAC RS transmission scheme is applied, for acertain purpose, a scheme for transmitting RSs on a per transmissionantenna or transmission layer basis and a scheme for allocating an indexmay be considered. Tx antenna/layer configuration may vary according toUEs. For example, in the case of 2Tx antenna configuration or 2-layertransmission, antenna port, indexes or layer port indexes #i and #(i+1)are specified on a per transmission antenna or transmission layer basis(i≧0). As another example, in the case of 4Tx antenna configuration or4-layer transmission, antenna port indexes or layer port indexes #i,#(i+1), #(i+2) and #(i+3) may be specified on a per transmission antennaor transmission layer basis. At this time, a scheme for applying theTDM-based CAZAC RSs with relatively excellent channel estimationperformance to q antenna ports from a low antenna port index inascending order, generating sequences using a method different from theabove method and applying RSs mapped to physical resources to theremaining antenna ports is proposed.

In addition to content of the UL, grant channel, SRS should be generatedand applied on a per antenna port or layer port basis according to theUL Tx antenna/layer configuration even in SRS design. At this time, inorder to provide extended multiplexing capacity, the transmission periodof the SRS per antenna port may be adjusted and defined in the timedomain. In one embodiment of the present invention, under the conditionthat the same multiplexing capacity is provided to p transmissionantennas or transmission layers in the same sequence design environmentas the SRS of a single antenna, the transmission periods of the SRSs ofthe time domain of a certain UE are equal and a method for sequentiallytransmitting the SRS per antenna or layer of the UE is applicable.Alternatively or simultaneously, SRS code for providing the extendedcapacity may be designed in association with a frequency domaindistributed, comb scheme so as to support efficient CDM/FDM multiplexingcapacity. Specifically, in consideration of a part or all of lowcorrelated root indexes v of the sequences in a state in which not onlycyclic shift u available in the code sequence level but also thesequence level scrambling are applied, code sequence resources may beincreased v-fold. At this time, the part of the low correlated rootindexes may indicate root indexes corresponding to the base sequenceswithin a group if UL DM-RSs are grouped. The low correlated root indexesare transmitted to the UE through L1/L2 control signaling orhigher-layer RRC signaling.

If subcarriers, which are physical resources to which sequence elementsare mapped, are mapped at a fixed offset interval using the distributedcomb scheme, a comb offset value may be adjusted according to channelconditions, SRS transmission load or time required for channel sounding.Alternatively or simultaneously, a limited sounding band (e.g., 5 MHz)is specified with respect to the entire system bandwidth (e.g., 20 MHz)to which the SU-MIMO is mapped, sounding and packet scheduling areperformed within the limited band and a virtual sub system, band for aplurality of UL SU-MIMO schemes is divided, and used, thereby supportingmultiplexing capacity in the frequency domain. The offset, value or thesounding band, of the distributed comb scheme is transmitted to the UEthrough L1 (first layer)/L2 (second layer) control signaling orhigher-layer RRC signaling.

(3) Configuration of MCS Indication Content for n Codewords

A method of allocating s bits so as to apply one MCS in a state in whicha single HARQ process is specified with respect to n codewords andtransmitting the MCS from a base station to a UE, a method of allocatings*n bits and transmitting an MCS per codeword without compressionthrough an UL grant channel in consideration of error detection abilityof n codewords, channel estimation ability of each antenna, and anoptimal Precoding matrix Indication (PMI) computation state of areception base station, and a method of allocating a total ofs+(s−δ)*(n−1) bits by summing s bits representing an MCS value of areference codeword and (s−δ)*(n−1) bits representing a differencebetween s and δ of the remaining n−1 codewords may be applied. Theselection of the method of specifying the MCS according to the codewordsmay be independent of the selection of the HARQ process indicationmethod. That is, during a single HARQ process, a. single ACK/NACKinformation feedback method is applied to MCW SU-MIMO transmission andcontrol information for specifying the MCS according to codewords may besignaled to a UE, through an UL grant PDCCH.

Up to now, the HARQ process indication method, the method of indicatingthe cyclic shift of the DM-RS and the method of indicating the MCS forthe codewords on the assumption that a single ACK/NACK is transmitted inUL MCW SU-MIMO have been described.

Hereinafter, a method of transmitting multiple ACKs/NACKs in UL MCWSU-MIMO will be described and then a PHICH resource allocation method, aHARQ process indication method, a method of indicating a cyclic shift ofa DM-RS, and a method of indicating an MCS for codewords when multipleACKs/NACKs are transmitted will be described.

2. Method of Transmitting Multiple ACKs/NACKs Using UL MCW SU-MIMO

In certain UL data transmission, if MCW SU-MIMO is used, HARQ processescorresponding in number to the number of codewords may be activatedunder change impact of the conventional LTE system in transmission usingn (1≦n≦2 or 1≦n≦4) codewords according to a codeword-to-layer mappingrule on a per rank basis. That is, DL ACK/NACK information transmissionmay be defined with respect to transmission on a per codeword basis.Hereinafter, the present invention proposes a method of receivingcodewords from a certain UE using MCW SU-MIMO, performing errordetection, utilizing a CRC on a per codeword basis using the codewordsin Successive Interference Cancellation (SIC) decoding, and transmittingindividual ACK/NACK information through a downlink PHICH with respect toall n codewords.

(1) PHICH Resource Assignment Method

The number of PHICH groups on a downlink PHICH for UL transmissionspecified in the conventional LTE system without MCW SU-MIMO needs to bedetermined on the assumption that the ACK/NACK for UL transmission isindividually indicated on a per codeword basis in a state in which MCWSU-MIMO is additionally applied in the LTE-A system. That is, when theamount of ACK/NACK information to be transmitted from a certain cell,base station or relay node in downlink must be increased due tointroduction of UL MCW SU-MIMO and the number of PHICH groups is set toa constant with respect to all subframes based on the maximum amount ofPHICH resources required in an UL system bandwidth, as MCW SU-MIMO isnewly introduced into UEs of the LTE-A system, the number of PHICHgroups must be set based on the amount of PHICH resources which is equalto or less than two times that of the LTE system.

A Physical Downlink Control Channel (PDCCH) is transmitted throughfirst, three or less OFDM symbols of each subframe, and the number ofOFDM symbols may be adjusted to 1 to 3 according to downlink controlchannel overhead. A channel used to adjust the number of OFDM symbolsfor the PDCCH for each subframe is a Physical Control Format IndicatorChannel. (PCFICH) and a channel used to transmitACKnowledgement/Negative ACKnowledgement (ACK/NACK) information, for anUL data channel is a Physical Hybrid-ARQ Indicator Channel (PHICH). Inaddition, a control channel used to send control information fordownlink data transmission or UL data transmission is a PhysicalDownlink Control Channel (PDCCH).

The PHICH transmits ACK/NACK for an UL data channel. Several PHICHgroups are included in one subframe, and one PHICH group includesseveral. PHICHs. Accordingly, PHICHs of several UEs are included in onePHICH group. The allocation of PHICHs to the UEs in several PHICH groupsis performed, using a lowest PRB index of PUSCH resource allocation anda frequency cyclic shift of a DM-RS transmitted through a UL grantsignal. PHICH channel resources are index pairs of n_(PHICH)^(group),n_(PHICH) ^(seq)). Here, n_(PHICH) ^(group) of n_(PHICH)^(group),n_(PHICH) ^(seq)) denotes a PHICH group index and n_(PHICH)^(seq) denotes an orthogonal sequence index within the PHICH group.

PHICH resources may be allocated, using only some (that is, PHICH groupsbased on the number of PHICHs defined in the conventional LTE system) ofan increased number of PHICH groups defined in the UL transmission ofthe UEs of the conventional LTE system. As a method of allocating PHICHresources to the UEs of the conventional LTE system, and supportingbackward compatibility from the viewpoint of PDCCH resource mapping, avalue Ng of a cell-specific Radio Resource Control (RRC) parameter isalways set to be greater than a necessary value and DL PHICH resourcesamong PHICH groups calculated based on the set value of Ng are allocatedto the UEs of the LTE-A system. PHICH allocation may be performed basedon a rule of minimizing collision with allocation of PHICH to the UEs ofthe conventional LTE system. Several embodiments of the method ofcalculating the number of PHICH groups are proposed.

1) First Method of Calculating Number of DL PHICH Groups

The number of DL PHICH groups may be calculated using Equation 1.

$\begin{matrix}{N_{PHICH}^{group} = \left\{ \begin{matrix}\left\lceil {N_{g}\left( {{N_{RB}^{DL} \cdot N_{C}}\text{/}8} \right)} \right\rceil & {{for}\mspace{14mu} {normal}\mspace{14mu} {cyclic}\mspace{14mu} {prefix}} \\{2 \cdot \left\lceil {N_{g}\left( {{N_{RB}^{DL} \cdot N_{C}}\text{/}8} \right)} \right\rceil} & {{for}\mspace{14mu} {extended}\mspace{14mu} {cyclic}\mspace{14mu} {prefix}}\end{matrix} \right.} & {{Equation}\mspace{14mu} 1}\end{matrix}$

In Equation 1, N_(g)ε{1/6,1/2,1/2} may be provided by higher layersignaling and N_(g) may scale the number of PHICH groups to be differentin DL and UL system bands. That is, N_(g) serves to adjust the number ofPHICHs according to current circumstances. In equation 1, N_(RB) ^(DL)denotes the number of resource blocks available in a DL system band andN_(c) denotes the maximum number of codewords (that is, the number ofencoding blocks) during UL transmission in a cell, a base station or asystem.

2) Second Method of Calculating Number of DL PHICH Groups

Without using N_(g) in the equation as a new parameter, an equation ofextending the range of the value N_(g) provided by conventional higherlayer signaling and extending a bit, size of an L1 parameter associatedtherewith from 2 bits to 3 bits so as to calculate the number of DLPHICH groups may be defined and expressed by Equation 2.

$\begin{matrix}{N_{PHICH}^{group} = \left\{ \begin{matrix}\left\lceil {N_{g}\left( {N_{RB}^{DL}\text{/}8} \right)} \right\rceil & {{for}\mspace{14mu} {normal}\mspace{14mu} {cyclic}\mspace{14mu} {prefix}} \\{2 \cdot \left\lceil {N_{g}\left( {N_{RB}^{DL}\text{/}8} \right)} \right\rceil} & {{for}\mspace{14mu} {extended}\mspace{14mu} {cyclic}\mspace{14mu} {prefix}}\end{matrix} \right.} & {{Equation}\mspace{14mu} 2}\end{matrix}$

In Equation 2, the range of N_(g) may be defined as one ofN_(g)ε{1/6,1/3,1/2,1,2,4}, N_(g)ε{1/6,1/3,1/2,1,2,3,4} andN_(g)ε{1/6,1/4,1/3,1/2,1,2,3,4}. A series of cell-specific RRCparameters representing the value N_(g) of the UEs of the LTE-A systemto which UL SU-MIMO or carrier aggregation is applied may be newlydefined so as to be distinguished from cell-specific RRC parametersrepresenting the value N_(g) of the UEs of the conventional LTE system,in consideration of backward compatibility with the UEs of theconventional LTE system.

3) Third method of Calculating Number of DL PHICH Groups

Instead of N_(RB) ^(DL), an equation of calculating the number of DLPHICH groups using N_(RB) ^(DL) which is the number of resource blocksavailable in a UL system, band may be defined and expressed by Equation3.

$\begin{matrix}{N_{PHICH}^{group} = \left\{ \begin{matrix}\left\lceil {N_{g}\left( {{N_{RB}^{UL} \cdot N_{C}}\text{/}8} \right)} \right\rceil & {{for}\mspace{14mu} {normal}\mspace{14mu} {cyclic}\mspace{14mu} {prefix}} \\{2 \cdot \left\lceil {N_{g}\left( {{N_{RB}^{UL} \cdot N_{C}}\text{/}8} \right)} \right\rceil} & {{for}\mspace{14mu} {extended}\mspace{14mu} {cyclic}\mspace{14mu} {prefix}}\end{matrix} \right.} & {{Equation}\mspace{14mu} 3}\end{matrix}$

In Equation 3, N_(g)ε{1/6,1/2,1/2} may be provided by higher layersignaling and Na may scale the number of PHICH groups to be different inDL and UL system bands. That is, N_(g) serves to adjust the number ofPHICHs according to current circumstances. In Equation 1, N_(RB) ^(DL)denotes the number of resource blocks available in a DL system band andN_(c) denotes the maximum number of codewords (that is, the number ofencoding blocks) during UL transmission in a cell, a base station or asystem.

In thee method of defining the number of PHICH groups, even in the LTEsystem, N_(c) may be set to 1, the range of N_(g) may be defined asN_(g)ε{1/6,1/2,1/2} or the range of N_(g) may be defined with respect toa plurality of cases or may be defined as a constant of 1.

4) Fourth Method of Calculating Number of DL PHICH Groups

N_(RB) ^(DL), which is the number of resource blocks available in a ULsystem band, is used instead of N_(RB) ^(DL). Without using N_(c) in theequation as a new parameter, an equation extending the range of thevalue Na provided by conventional higher layer signaling and extending abit, size of an L1 parameter associated therewith from 2 bits to 3 bitsso as to calculate the number of DL PHICH groups may be defined andexpressed by Equation 4.

$\begin{matrix}{N_{PHICH}^{group} = \left\{ \begin{matrix}\left\lceil {N_{g}\left( {N_{RB}^{UL}\text{/}8} \right)} \right\rceil & {{for}\mspace{14mu} {normal}\mspace{14mu} {cyclic}\mspace{14mu} {prefix}} \\{2 \cdot \left\lceil {N_{g}\left( {N_{RB}^{UL}\text{/}8} \right)} \right\rceil} & {{for}\mspace{14mu} {extended}\mspace{14mu} {cyclic}\mspace{14mu} {prefix}}\end{matrix} \right.} & {{Equation}\mspace{14mu} 4}\end{matrix}$

In Equation 4, the range of N_(g) may be defined as one ofN_(g)ε{1/6,1/3,1/2,1,2,4}, N_(g)ε{1/6,1/3,1/2,1,2,3,4} andN_(g)ε{1/6,1/4,1/3,1/2,1,2,3,4}. In addition, the range of N_(g) may bedefined with respect to a plurality of cases and may be defined asN_(g)ε{1,2}, N_(g)ε{1,2,4}, N_(g)ε{1/2,1,2,4} or a constant of 1. In thefourth method of calculating the number of PHICH groups, a method ofcalculating the number of PHICH groups using the parameter N_(RB) ^(UL)is applicable to the equations of the first and second methods of(calculating the number of PHICH groups by replacing N_(RB) ^(DL) withN_(RB) ^(UL).

A series of cell-specific RRC parameters representing the value N_(g) ofthe UEs of the LTE-A system to which UL SU-MIMO or carrier aggregationis applied may be newly defined so as to be distinguished fromcell-specific RRC parameters representing the value N_(g) of the UEs ofthe conventional LTE system, in consideration of backward compatibilitywith the UEs of the conventional LTE system.

Before description of resource group alignment of individual PHIICHgroups based on the number of PHICH groups, layer mapping and precodingscheme, in order to support backward and forward compatibility of the UEof the LTE system and the UE of the LTE-A system with the LTE-A and LTEnetworks, even in at state in which the number of DL transmissionantennas of the LTE-A system is eight, DL PDCCH, PCFICH and PHICH aretransmitted using a transmit diversity scheme based on four transmissionantennas.

In addition, even in a state in which eight transmission antennas areused, the amount and positions of subcarrier resources in a frequencydomain used for DL RS transmission of first and second OFDM symbols maybe set to be equal to those of the conventional LTE system. Thus, whileresource group alignment of PDCCH, PCFICH and PHICH, layer mapping andprecoding scheme are maintained similar to the LTE scheme, compatibilityis supported.

Based on the number of PHICH groups obtained by the method proposed bythe present invention, resource group alignment, layer mapping andprecoding scheme, PHICH resource assignment for UL transmission of anindividual UE may be expressed by a pair (n_(PHICH) ^(group), n_(PHICH)^(seq)) of the index n_(PHICH) ^(group) for the PHICH group and theorthogonal sequence index n_(PHICH) ^(seq) generated due to spreadingcode and 1−Q multiplexing within the PHICH group.

In a state in which PHICH resource allocation is performed in a certainUE according to individual codewords or codeword groups by introductionof UL SU-MIMO based on multiple codewords, the PHICH resource pair maybe expressed by (n_(PHICH) ^(group)(i), n_(PHICH) ^(seq)(i)) withrespect to a certain codeword index i (i=1, . . . , n where n (−1, . . ., N_(PHICH) ^(max)). , At this time, i denotes the number of codewordsused for UL SU-MIMO transmission, and N_(PHICH) ^(max) denotes apredetermined maximum number of PHICH channels in UL SU-MIMO. N_(PHICH)^(max) may be equal to a maximum number of codewords available in ULSU-MIMO or the number of groups of codewords available in UL SU-MIMO.

The PHICH group index n_(PHICH) ^(group)(i) and the PHICH orthogonalsequence index n_(PHICH) ^(seq)(i) proposed by the present invention aredetermined by a cyclic shift index of a UL DM-RS used for ULtransmission and a lowest index value of physical resource blockallocation. At this time, a cyclic shift index of a UL DM-RS is used asa parameter to allocate different PHICH resources to PHICHs required inUL SU-MIMO to which multiple codewords are applied. If UL PUSCHtransmission is not performed through a UL grant PDCCH, the cyclic shiftindex of the UL DM-RS may be a predetermined value (e.g., an index #0)or may be specified by a UE or a. relay node when a transmission sessionis activated through RRC parameter signaling or L1/L2 PDCCH signaling ofthe UE or the relay node.

The number of antenna ports used for UL SU-MIMO transmission in acertain UE may be P, the number of codewords used in SU-MIMO is amaximum of N, and an individual antenna port index p (p=1, . . . , P−1)may be defined. In UL SU-MIMO, a total of P indexes of RS sequencesgenerated using the cyclic shift of the UL DM-RS and/or other method areallocated on a per antenna port basis. If P and n are the same,individual RS sequence indexes may be used as DM-RS sequence indexes (orcyclic shift indexes) n_(RS) ^(seq)(i) per n codewords used in a processof deriving values of n_(PHICH) ^(group)(i) and n_(RS) ^(seq)(i). Incontrast, if P is greater than n, indexes which may be used as a valueof n_(RS) ^(seq)(i) among the RS sequence indexes must be selected.

As the selection method, a method, of selecting n indexes from among PRS sequence indexes in ascending order, a method of selecting n everyother RS sequence indexes (e.g., first, third, fifth indexes) inascending order, or a method of selecting indexes using a rule based ona certain function, a method of randomly selecting indexes, or a methodof selecting indexes in order of a first index, a last index, a secondindex, and the second to last index may be used. In addition, if P DM-RSsequences are generated using the method of generating DM-RS sequencesusing a CAZAC or ZC method or the method of generating DM-RS sequencesusing another method, n indexes may be selected from among cyclic shiftindexes generated using the method of generating the DM-RS sequencesusing the CAZAC or ZC method, using any one of the methods of thepresent invention.

The values of n_(PHICH) ^(group)(i) and n_(PHICH) ^(seq)(i) may bederived based on n_(RS) ^(seq)(i) of an individual codeword index iusing the above method. Alternatively, the values of n_(PHICH)^(group)(i) and n_(PHICH) ^(seq)(i) may be adjusted and derived using acertain function f(i) in addition to n_(RS) ^(seq)(i) of the codewordindex i so as to minimize collision with PHICH channel resourceallocation of the UEs of the conventional LTE system. The value i of thefunction f(i) is configured in a higher layer and may be signaled to theUE of the LTE-A system through a series of UE-specific RRC signaling.Hereinafter, various methods of computing the PHICH group indexn_(PHICH) ^(group)(i) and the PHICH orthogonal sequence index n_(PHICH)^(seq)(i) are proposed.

1) First Method

The PHICH group index n_(PHICH) ^(group)(i) and the PHICH orthogonalsequence index n_(PHICH) ^(seq)(i) may be computed by Equation 5.

$\begin{matrix}{{{n_{PHICH}^{group}(i)} = {{\left( {I_{{PRB}\; \_ \; {RA}}^{{lowest}\mspace{11mu} \_ \; {index}} + {n_{RS}^{seq}(i)}} \right){mod}\; N_{PHICH}^{group}} + {I_{PHICH}N_{PHICH}^{group}}}}{{n_{PHICH}^{seq}(i)} = {\left( {\left\lfloor {I_{{PRB}\; \_ \; {RA}}^{{lowest}\mspace{14mu} {index}}\text{/}N_{PHICH}^{group}} \right\rfloor + {n_{RS}^{seq}(i)}} \right){mod}\mspace{11mu} 2N_{SF}^{PHICH}}}{I_{PHICH} = \left\{ \begin{matrix}1 & \begin{matrix}{{for}\mspace{14mu} {TDD}\mspace{14mu} {UL}\text{/}{DL}\mspace{14mu} {configuration}\mspace{14mu} 0\mspace{14mu} {with}} \\{{{PUSCH}\mspace{14mu} {transmission}\mspace{14mu} {in}\mspace{14mu} {subframe}\mspace{14mu} n} = {4\mspace{14mu} {or}\mspace{14mu} 9}}\end{matrix} \\0 & {otherwise}\end{matrix} \right.}} & {{Equation}\mspace{11mu} 5}\end{matrix}$

where, N_(SF) ^(PHICH) denotes the size of a Spreading Factor (SF) usedin PHICH modulation, and I_(PRB) _(_) _(RA) ^(lowest) ^(index) denotes alowest index of a Physical Resource Block (PRB) of UL resourceallocation. N_(PHICH) ^(group) denotes the number of PHICH groupsconfigured by a higher layer.

2) Second Method

The PHICH group index n_(PHICH) ^(group)(i) and the PHICH orthogonalsequence index n_(PHICH) ^(seq)(i) may be computed by Equation 6.

$\begin{matrix}{{{n_{PHICH}^{group}(i)} = {{{\left( {I_{{PRB}\; \_ \; {RA}}^{{lowest}\mspace{11mu} \_ \; {index}} + {n_{RS}^{seq}(i)} + {f(i)}} \right){mod}\; N_{PHICH}^{group}} + {I_{PHICH}N_{PHICH}^{group}{n_{PHICH}^{seq}(i)}}} = {\left( {\left\lfloor {I_{{PRB}\; \_ \; {RA}}^{{lowest}\_ {index}}\text{/}N_{PHICH}^{group}} \right\rfloor + {n_{RS}^{seq}(i)} + {f(i)}} \right){mod}\mspace{11mu} 2N_{SF}^{PHICH}}}}{I_{PHICH} = \left\{ \begin{matrix}1 & \begin{matrix}{{for}\mspace{14mu} {TDD}\mspace{14mu} {UL}\text{/}{DL}\mspace{14mu} {configuration}\mspace{14mu} 0\mspace{14mu} {with}} \\{{{PUSCH}\mspace{14mu} {transmission}\mspace{14mu} {in}\mspace{14mu} {subframe}\mspace{14mu} n} = {4\mspace{14mu} {or}\mspace{14mu} 9}}\end{matrix} \\0 & {otherwise}\end{matrix} \right.}} & {{Equation}\mspace{14mu} 6}\end{matrix}$

where, N_(SF) ^(PHICH) denotes the size of a Spreading Factor (SF) usedin PHICH modulation, and I_(PRB) _(_) _(RA) ^(lowest) ^(index) denotes alowest index of a Physical Resource Block (PRB) of UL resourceallocation. N_(PHICH) ^(group) much denotes the number of PHICH groupsconfigured by a higher layer. In addition, f(i) denotes a function forproviding a unique codeword offset and may be a function f(i)=i or asconstant which is previously set on a per codeword index basis.

3) Third Method

The PHICH group index n_(PHICH) ^(group)(i) and the PHICH orthogonalsequence index n_(PHICH) ^(seq)(i) may be computed by Equation 7.

$\begin{matrix}{{{n_{PHICH}^{group}(i)} = {{{\left( {I_{{PRB}\; \_ \; {RA}}^{{lowest}\mspace{11mu} \_ \; {index}} + {n_{RS}^{seq}(i)} + {f(i)}} \right){mod}\; N_{PHICH}^{group}} + {I_{PHICH}N_{PHICH}^{group}{n_{PHICH}^{seq}(i)}}} = {\left( {\left\lfloor {I_{{PRB}\; \_ \; {RA}}^{{lowest}\_ {index}}\text{/}N_{PHICH}^{group}} \right\rfloor + {n_{RS}^{seq}(i)} + {f(i)}} \right){mod}\mspace{11mu} 2N_{SF}^{PHICH}}}}{I_{PHICH} = \left\{ \begin{matrix}1 & \begin{matrix}{{for}\mspace{14mu} {TDD}\mspace{14mu} {UL}\text{/}{DL}\mspace{14mu} {configuration}\mspace{14mu} 0\mspace{14mu} {with}} \\{{{PUSCH}\mspace{14mu} {transmission}\mspace{14mu} {in}\mspace{14mu} {subframe}\mspace{14mu} n} = {4\mspace{14mu} {or}\mspace{14mu} 9}}\end{matrix} \\0 & {otherwise}\end{matrix} \right.}} & {{Equation}\mspace{14mu} 7}\end{matrix}$

where, N_(SF) ^(PHICH) denotes the size of a Spreading Factor (SF) usedin PHICH modulation, and I_(PRB) _(_) _(RA) ^(lowest) ^(_) ^(index)denotes a lowest index of a Physical Resource Block (PRB) of UL resourceallocation. N_(PHICH) ^(group) denotes the number of PHICH groupsconfigured by a higher layer. In addition, f(i)=α·i denotes a functionfor providing a unique codeword offset and α may be a non-zero constantprovided by higher layer signaling.

4) Fourth Method

The PHICH group index n_(PHICH) ^(group)(i) and the PHICH orthogonalsequence index n_(PHICH) ^(seq)(i) may be computed by Equation 8 .

$\begin{matrix}{{{n_{PHICH}^{group}(i)} = {{{\left( {I_{{PRB}\; \_ \; {RA}}^{{lowest}\mspace{11mu} \_ \; {index}} + {{n_{RS}^{seq}(i)} \cdot {f(i)}}} \right){mod}\; N_{PHICH}^{group}} + {I_{PHICH}N_{PHICH}^{group}{n_{PHICH}^{seq}(i)}}} = {\left( {\left\lfloor {I_{{PRB}\; \_ \; {RA}}^{{lowest}\mspace{14mu} {index}}\text{/}N_{PHICH}^{group}} \right\rfloor + {{n_{RS}^{seq}(i)} \cdot {f(i)}}} \right){mod}\mspace{11mu} 2N_{SF}^{PHICH}}}}{I_{PHICH} = \left\{ \begin{matrix}1 & \begin{matrix}{{for}\mspace{14mu} {TDD}\mspace{14mu} {UL}\text{/}{DL}\mspace{14mu} {configuration}\mspace{14mu} 0\mspace{14mu} {with}} \\{{{PUSCH}\mspace{14mu} {transmission}\mspace{14mu} {in}\mspace{14mu} {subframe}\mspace{14mu} n} = {4\mspace{14mu} {or}\mspace{14mu} 9}}\end{matrix} \\0 & {otherwise}\end{matrix} \right.}} & {{Equation}\mspace{14mu} 8}\end{matrix}$

where, N_(SF) ^(PHICH) denotes the size of a Spreading Factor (SF) usedin PHICH modulation, and I_(PRB) _(_) _(RA) ^(lowest) ^(_) ^(index)denotes a lowest index of a Physical Resource Block (PRB) of UL resourceallocation. N_(PHICH) ^(group) denotes the number of PHICH groupsconfigured by a higher layer. In addition, f(i) denotes a function forproviding a unique codeword offset and may be a function f(i)=i or anon-zero constant which is previously set on a per codeword index basis.

5) Fifth Method

The PHICH group index n_(PHICH) ^(group)(i) and the PHICH orthogonalsequence index n_(PHICH) ^(seq)(i) may be computed by Equation 9.

$\begin{matrix}{{{n_{PHICH}^{group}(i)} = {{{\left( {I_{{PRB}\; \_ \; {RA}}^{{lowest}\mspace{11mu} \_ \; {index}} + {{n_{RS}^{seq}(i)} \cdot {f(i)}}} \right){mod}\; N_{PHICH}^{group}} + {I_{PHICH}N_{PHICH}^{group}{n_{PHICH}^{seq}(i)}}} = {\left( {\left\lfloor {I_{{PRB}\; \_ \; {RA}}^{{lowest}\_ {index}}\text{/}N_{PHICH}^{group}} \right\rfloor + {{n_{RS}^{seq}(i)} \cdot {f(i)}}} \right){mod}\mspace{11mu} 2N_{SF}^{PHICH}}}}{I_{PHICH} = \left\{ \begin{matrix}1 & \begin{matrix}{{for}\mspace{14mu} {TDD}\mspace{14mu} {UL}\text{/}{DL}\mspace{14mu} {configuration}\mspace{14mu} 0\mspace{14mu} {with}} \\{{{PUSCH}\mspace{14mu} {transmission}\mspace{14mu} {in}\mspace{14mu} {subframe}\mspace{14mu} n} = {4\mspace{14mu} {or}\mspace{14mu} 9}}\end{matrix} \\0 & {otherwise}\end{matrix} \right.}} & {{Equation}\mspace{14mu} 9}\end{matrix}$

where, N_(SF) ^(PHICH) denotes the size of a Spreading Factor (SF) usedin PHICH modulation, and I_(PRB RA) ^(lowest) ^(_) ^(index) denotes alowest index of a Physical Resource Block (PRB) of UL resourceallocation. N_(PHICH) ^(group) denotes the number of PHICH groupsconfigured by a higher layer. In addition, f(i)=α·i+1 or f(i)=α·(i+1)denotes a function for providing a unique codeword offset and α may be anon-zero constant provided by higher layer signaling.

Any one of the above-proposed methods of deriving the values n_(PHICH)^(group)(i) and n_(PHICH) ^(seq)(i) may be used in association with anyone of the above-described methods of defining the number PHICH groups.The method of calculating the number of PHICH groups and the PHICHallocation methods associated therewith are not limited to UL, SU-MIMOand are applicable to all cases requiring allocation of a plurality ofPHICHs to a certain UE due to introduction of LTE-A technology such asUL carrier aggregation or UL coordinated Multi-point (CoMP).

Up to now, PHICH resource allocation was described. Hereinafter, on theassumption that multiple ACKs/NACKs are transmitted using UL MCWSU-MIMO, a HARQ process indication method, a DM-RS cyclic shift indexindication method, and a method of constructing MCS indication contentof n code words

(1) HARQ Process Indication

This is a field indicating a single or a plurality of HARQ processeswith respect to n codewords. Even in the case where a HARQ process isindividually allocated to a codeword, if a HARQ index of a certainreference codeword is specified while being represented by 3 bits, theHARQ processes of the other n−1 codewords are automatically calculatedbased on a fixed offset. Additional bits indicating the codewords may beadded to the 3-bit HARQ process indication field or may be defined as aseparate explicit codeword indication field.

(2) Method of Indicating Cyclic Shift Index Demodulation-ReferenceSignal (DM-RS)

A method of indicating a cyclic shift index of a DM-RS on an UL channelwill be divided into three cases as follows.

1) First Case

In the first case, in the implementation of the conventional UL SU-MIMO,there is a need for RSs for providing channel estimation fordemodulation and decoding of p (p≦m) reception data streams according toa transmission (Tx) antenna/layer configuration of a UE, which isdefined by m (for example, m may be 2 or 4, 1 or 2, or 3 or 4)representing the number of transmission antennas (virtual antennas orphysical antennas) or the number of virtual antennas or the number oftransmission layers. At this time, q (q≦p) RSs among the P RSs may bespecified as the cyclic shift version of the QPSK-basedcomputer-generated sequence of a low correlation property of the case of1 RB/2 RB or the CAZAC base sequence having the length of a region fordata transmission on frequency subcarriers in certain OFDM, SC-FDMA orclustered SC-FDMA symbols (as TDM, one OFDM, SC-FDMA or clusteredSC-FDMA symbol may be specified or a plurality of OFDM, SC-FDMA orclustered SC-FDMA symbols may be specified, for RS transmission).

RS indexes, which are used as a criterion for indicating the q usedcyclic shift indexes, may be 3 bits ling. As the remaining q−1 cyclicshift indexes are automatically specified using sin offset, which isvariably specified according to system circumstances by an arbitraryrule, a fixed offset or a fixed selection rule, it is possible tominimize overhead when the UE signals the used cyclic shift indexes.

2) Second Case

In the second case, as described in the first case, a combination ofcyclic shifts for the remaining q−1 RSs different from a cyclic shiftindex for a RS which is used as a criterion for signaling cyclic shiftindexes for q RSs may be specified or cyclic shift indexes for q RSs maybe specified as 3+α (0<α<3*(q−1)) bits using a certain informationcompression rule. For example, α may be defined as a bit value of a sumof all or part of q−1 RS sequences of values (values less than 3 bits)representing a difference between the indexes for the RSs and the cyclicshift index for the RS which is used as the criterion.

3) Third Case

In the third case, as described in the first case, cyclic shifts for qRSs are explicitly specified on the UL grant channel with respect to qRSs. In this case, the size of the RS cyclic shift field in the (controlinformation payload of the UL channel may be 3*q if the bit size of theindividual cyclic shift field is 3 bits.

If p and q are the same in the first cases, RSs of CAZAC sequence of adata band in one or more OFDM, SC-FDMA or clustered SC-FDMA symbols areused as all RSs for all antennas. In the present invention, it isassumed that the antenna includes a virtual antenna, a physical antennaand a transmission layer.

If p and q are different in the first case, as the number of cyclicshifts which can be provided such that the CAZAC RS sequencestransmitted through certain OFDM, SC-FDMA or clustered SC-FDMA symbolsare orthogonal, in a state in which the cyclic shifts for p RSs are notsufficient to enable allocation of one OFDM, SC-FDMA or clusteredSC-FDMA symbol to each slot, OFDM, SC-FDMA or clustered SC-FDMA symbolsfor transmitting a plurality of RS sequences are allocated as in thefirst case and the additional CAZAC RS sequences may be continuouslyallocated. However, since such an allocation scheme directlydeteriorates UL throughput, heterogeneous RSs having low overhead, whichare generated using different methods, are used along with the q CAZACRSs. The number of heterogeneous RSs is set to p−q which is equal to orgreater than 0. At this time, for entire overhead adjustment, q may be0.

As an embodiment of the design of the RS different from the conventionalTDM (OFDM, SC-FDMA or clustered SC-FDMA symbols)-CDM (CAZAC) sequences,in the case of using SC-FDMA or clustered SC-FDMA, a scheme forinserting RSs into a time sample region within arbitrary transmissionsymbols or r (r≧1) predetermined time domain symbol positions at aprevious stage of the DFT or a next stage of the IDFT (or IFFT) may beconsidered.

The RSs inserted into the time domain at the previous stage of the DFTare subjected to spread spectrum spreading to all subcarriers of thefrequency domain within the DFT region through DFT, are subjected toIFFT, are transmitted to a receiver through a channel, and are subjectedto FFT and IFFT in the receiver, thereby extracting channel informationof the antenna on a band for transmitting data from r RSs of the symbolpositions.

A scheme for directly mapping RS sequences to a frequency domain withoutperforming DFT and performing IFFT with respect to the mapped RSsequences and a scheme for directly mapping RS sequences to an OFDM,SC-FDMA or clustered SC-FDMA symbol region on a next stage of IFFT maybe applied. The OFDM, SC-FDMA or clustered SC-FDMA symbol-region may bethe entire OFDM, SC-FDMA or clustered SC-FDMA symbol region or a partialtime sample region of the OFDM, SC-FDMA or clustered SC-FDMA symbols. Inthe case where RSs are inserted into OFDM, SC-FDMA or clustered SC-FDMAsymbols for transmitting data, the fixed positions in the OFDM, SC-FDMAor clustered SC-FDMA symbols may be specified and the RSs are insertedat the fixed positions or the RSs may be inserted at positions generatedfrom resource block indexes and/or cell IDs according to a certain rule.In the case where overhead of additional RSs is added, from theviewpoint of data and multiplexing, resources to which RSs will bemapped may be secured using puncturing of symbols for transmitting dataor rate matching.

The UL RS design scheme is applicable not only to the UL SU-MIMO schemebut also to non-spatial multiplexing schemes. In the case of DM-RS,under situation that DM-RS transmission OFDM, SC-FDMA or clusteredSC-FDMA symbols designed based on the conventional TDM-C DM are present,the UL-RS design scheme may be additionally defined in different OFDM,SC-FDMA or clustered SC-FDMA symbols. Alternatively, the UL-RS designscheme may be applied to replace the scheme designating DM-RStransmission OFDM, SC-FDMA or clustered SC-FDMA symbols designed basedon the conventional TDM-CDM. The UL RS design scheme is applicable tonot only the DM-RS but also the SRS.

If the OFDM, SC-FDMA or clustered SC-FDMA scheme is applied to ULtransmission, a pattern in which RSs are inserted at fixed frequencysubcarrier positions within resource blocks in resource block units maybe defined. Such a pattern may be cell-specifically defined by a certainfunction or rule using a cell ID as an input signal. The resource blockincludes both a virtual resource block and a physical resource block.Accordingly, RSs may be inserted upon symbol mapping before IFFT inputof the transmitter. If RSs are inserted into one or more OFDM, SC-FDMAor clustered SC-FDMA symbols for transmitting data, the RSs may beinserted into fixed positions or positions generated from a resourceblock index and/or cell ID according to a certain rule. At this time,resources to which RSs will be mapped may be secured using puncturing ofsymbols for transmitting data or rate matching.

In a certain system, with respect to p-q RSs among p RSs, in anenvironment in which an RS transmission scheme different from theconventional TDM-based CAZAC RS transmission scheme is applied, for acertain purpose, a scheme for transmitting RSs on a per transmissionantenna or transmission layer basis and a scheme for allocating anindex, may be considered. Tx antenna/layer configuration may varyaccording to UEs. For example, in the case of 2Tx antenna configurationor 2-layer transmission, antenna port indexes or layer port, indexes #iand #(i+1) are specified, on a per transmission antenna or transmissionlayer basis (i>0). As another example, in the case of 4Tx antennaconfiguration or 4-layer transmission, antenna port indexes or layerport indexes #i, #(i+1), #(i+2) and #(i+3) may be specified on a pertransmission antenna or transmission layer basis. At this time, a schemefor applying the TDM-based CAZAC RSs with relatively excellent channelestimation performance to q antenna ports from a low antenna port indexin ascending order, generating sequences using a method different fromthe above method and applying RSs mapped to physical resources to theremaining antenna ports is proposed.

In addition to content of the UL grant channel, SRS should be generatedand applied on a per antenna port or layer port basis according to theUL Tx antenna/layer configuration even in SRS design. At this time, inorder to provide extended multiplexing capacity, the transmission periodof the SRS per antenna port may be adjusted and defined in the timedomain. In one embodiment of the present invention, under the conditionthat the same multiplexing capacity is provided to p transmissionantennas or transmission layers in the same sequence design environmentas the SRS of a single antenna, the transmission periods of the SRSs ofthe time domain of a certain UL are equal and a method for sequentiallytransmitting the SRS per antenna or layer of the UE is applicable.Alternatively or simultaneously, SRS code for providing the extendedcapacity may be designed in association with a frequency domaindistributed comb scheme so as to support efficient CDM/FDM multiplexingcapacity. Specifically, in consideration of a part or all of lowcorrelated root indexes v of the sequences in a state in which not onlycyclic shift u available in the code sequence level but also thesequence level scrambling are applied, code sequence resources may beincreased v-fold. At this time, the part of the low correlated rootindexes may indicate root indexes corresponding to the base sequenceswithin a group if UL DM-RSs are grouped. The low correlated root indexesare transmitted to the UE through L1/L2 control signaling orhigher-layer RRC signaling.

If subcarriers, which are physical resources to which sequence elementsare mapped, are mapped at a fixed offset interval using the distributedcomb scheme, a comb offset value may be adjusted according to channelconditions, SRS transmission load or time required for channel sounding.Alternatively or simultaneously, a limited sounding band (e.g., 5 MHz)is specified with respect to the entire system bandwidth (e.g., 20 MHz)to which the SU-MIMO is mapped, sounding and packet scheduling areperformed within the limited band and a virtual sub system band for aplurality of UL SU-MIMO schemes is divided and used, thereby supportingmultiplexing capacity in the frequency domain. The offset value or thesounding band of the distributed comb scheme is transmitted to the UEthrough L1 (first layer)/L2 (second layer) control signaling orhigher-layer RRC signaling.

(3) Configuration of MCS Indication Content for n Codewords

Unlike a method of allocating s bits so as to apply to one MCS in astate in which a single or a plurality of HARQ processes is specifiedwith respect to n codewords and transmitting the MCS from a base stationto a UE, a method of allocating s*n bits and transmitting an MCS percodeword without compression through an UL grant channel inconsideration of error detection ability of n codewords, channelestimation ability of each antenna, and an optimal Precoding matrixIndication (PMI) computation state of a reception base station, and amethod of allocating a total of s+(s−δ)*(n−1) bits by summing s bitsrepresenting an MCS value of a reference codeword and (s−δ)*(n−1) bitsrepresenting a difference between s and δ of the remaining n−1 codewordsmay be applied. The selection of the method of specifying the MCSaccording to the codewords may be independent of the selection of theHARQ process indication method. That is, during a single HARQ process, asingle ACK/NACK information feedback method is applied to MCW SU-MIMOtransmission and control information for specifying the MCS according tocodewords may be signaled to a UE through an UL grant PDCCH.

All aspects of the present invention are applicable to directtransmission from a UE to an eNB, transmission from a UE to a relaynode, between relay nodes, and from a relay node to an eNB in a state inwhich relay transmission is implemented, and control signaling.

FIG. 11 is a block diagram showing the configuration of a device thatcan perform the present invention and which is applicable to a userequipment (UE) and a base station (BS). As shown in FIG. 11, the device110 includes a processing unit 111, a memory unit 112, a Radio Frequency(RF) unit 113, a display unit 114 and a user interface unit 115.Processing for a physical interface protocol layer is performed by theprocessing unit 111. The processing unit 111 provides a control planeand a user plane. Processing for each layer may be performed by theprocessing unit 111. The memory unit 112 may be electrically connectedto the processing unit 111 and stores an operating system, applicationprograms and general files. If the device 110 is a user equipment, thedisplay unit ill may display a variety of information and may beimplemented using a Liquid Crystal Display (LCD) or an Organic LightEmitting Diode (OLED). The user interface unit 115 may be combined witha known user interface such as a keypad or a touch screen. The RF unit113 may be electrically connected to the processing unit 111 so as totransmit or receive an RF signal.

The above-mentioned embodiments of the present invention are disclosedon the basis of a data communication relationship between a base stationand a mobile station. In this case, the base station is used sis aterminal node of a network via which the base station can directlycommunicate with the mobile station. Specific operations to be conductedby the base station in the present invention may also be conducted by anupper node of the base station as necessary.

In other words, it will be obvious to those skilled in the art thatvarious operations for enabling the base station to communicate with themobile station in a network composed of several network nodes includingthe base station will be conducted by the base station or other networknodes other than the base station. The term “Base Station” may bereplaced with a fixed station, Node-B, eNode-B (eNB), or an access pointas necessary. The term “mobile station” may also be replaced with theterms user equipment (UE), mobile station (MS) or mobile subscriberstation (MSS) as necessary.

The following embodiments of the present invention can be implemented bya variety of means, for example, hardware, firmware, software, or acombination thereof.

In the case of implementing the present invention by hardware, thepresent invention can be implemented using application specificintegrated circuits (ASICs), digital signal processors (DSPs), digitalsignal processing devices (DSPDs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), a processor, a controller, amicrocontroller, a microprocessor, etc.

If operations or functions of the present invention are implemented byfirmware or software, the present invention can be implemented in theform of a variety of formats, for example, modules, procedures,functions, etc. The software code may be stored in a memory unit so asto be driven by a processor. The memory unit is located inside oroutside of the processor, so that it can communicate with theaforementioned processor via a variety of well-known parts.

The aforementioned embodiments are achieved by combination of structuralelements and features of the present invention in a predeterminedmanner. Each of the structural elements or features should be consideredselective unless specified otherwise. Each of the structural elements orfeatures may be implemented without being combined with other structuralelements or features. Also, some structural elements and/or features maybe combined with one another to constitute the embodiments of thepresent invention. The order of operations de scribe-d in theembodiments of the present invention may be changed. Some structuralelements or features of one embodiment may be included in anotherembodiment, or may be replaced with corresponding structural elements orfeatures of another embodiment.

Moreover, it will be apparent that some claims referring to specificclaims may be combined with other claims referring to the other claimsother than the specific claims to constitute the embodiment, or newclaims may be added by amendment after the application is filed.

The present invention is applicable to a user equipment, a base stationor other device of a radio mobile communication system.

If Single-User Multiple Input Multiple Output (SU-MIMO) based onmultiple codewords (MCW) is applied in uplink, transmission, it ispossible to reduce system complexity and to improve system managementflexibility.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1-10. (canceled)
 11. A method for a user equipment (UE) to transmitmultiple data units to a base station via multiple transmissionantennas, the method comprising: receiving, from the base station,downlink control information informing the UE of control information fortransmitting uplink data to the base station, wherein the downlinkcontrol information comprises: a demodulation reference signal (DMRS)cyclic shift index field having a predetermined length and modulationand coding scheme (MCS) information for each of the multiple data units;transmitting the multiple data units with multiple DMRSs to the basestation via the multiple transmission antennas based on the MCSinformation, wherein each of the multiple DMRSs is cyclic shifted withdifferent cyclic shift values, and wherein each value of the DMRS cyclicshift index field indicates a combination of different cyclic shiftvalues for each of the multiple DMRSs; and wherein the MCS informationincludes ‘n*s’ bit information, wherein the ‘n’ corresponds to a numberof the multiple data units, and the ‘s’ corresponds to a number of bitsfor indicating MCS information for one data unit
 12. The method of claim11, wherein a number of different combinations of different cyclic shiftvalues for each of the multiple DMRSs corresponds to a number of casesidentifiable by the DMRS cyclic shift index field having thepredetermined length.
 13. The method of claim 11, wherein thepredetermined length of the DMRS cyclic shift index field is the same asa length of the DMRS cyclic shift index field for indicating cyclicshift value for one DMRS.
 14. The method of claim 11, wherein thepredetermined length corresponds to a 3 bit length, and wherein 8combinations of different cyclic shift values for each of the multipleDMRSs are respectively predetermined based on the DMRS cyclic shiftindex field.
 15. A method for a base station to receive multiple dataunits from multiple transmission antennas of a user equipment (UE), themethod comprising: transmitting, to the UE, downlink control informationinforming the UE of control information for transmitting uplink data tothe base station, wherein the downlink control information comprises: ademodulation reference signal (DMRS) cyclic shift index field having apredetermined length, and modulation and coding scheme (MCS) informationfor each of the multiple data units; receiving, from the UE, themultiple data units with multiple DMRSs transmitted from the multipletransmission antennas, wherein each of the multiple DMRSs is cyclicshifted with different cyclic shift values, and wherein each value ofthe DMRS cyclic shift index field indicates a combination of differentcyclic shift values for each of the multiple DMRSs; and wherein the MCSinformation includes ‘n*s’ bit information, wherein the ‘n’ correspondsto a number of the multiple data units, and the‘s’ corresponds to anumber of bits for indicating MCS information for one data unit.
 16. Themethod of claim 15, wherein a number of different combinations ofdifferent cyclic shift values for each of the multiple DMRSs correspondsto a number of cases identifiable by the DMRS cyclic shift index fieldhaving the predetermined length.
 17. The method of claim 15, wherein thepredetermined length of the DMRS cyclic shift index field is the same asa length of the DMRS cyclic shift index field for indicating cyclicshift value for one DMRS.
 18. The method of claim 15, wherein thepredetermined length corresponds to a 3 bit length, and wherein 8combinations of different cyclic shift values for each of the multipleDMRSs are respectively predetermined based on the DMRS cyclic shiftindex field.
 19. An user equipment (UE) configured to transmit multipledata units to a base station, the UE comprising: a transceivercomprising multiple transmission antennas; and a processor connected tothe transceiver, wherein the processor controls the transceiver: toreceive, from the base station, downlink control information informingthe UE of control information for transmitting uplink data to the basestation, wherein the downlink control information comprises: ademodulation reference signal (DMRS) cyclic shift index field having apredetermined length and modulation and coding scheme (MCS) informationfor each of the multiple data units; to transmit the multiple data unitswith multiple DMRSs to the base station via the multiple transmissionantennas based on the MCS information, wherein each of the multipleDMRSs is cyclic shifted with different cyclic shift values, and whereineach value of the DMRS cyclic shift index field indicates a combinationof different cyclic shift values for each of the multiple DMRSs; andwherein the MCS information includes ‘n*s’ bit information, wherein the‘n’ corresponds to a number of the multiple data units, and the ‘s’corresponds to a number of bits for indicating MCS information for onedata unit
 20. A base station configured to receive multiple data unitsfrom multiple transmission antennas of a user equipment (UE), the basestation comprising: a transceiver configured: to transmit, to the UE,downlink control information informing the UE of control information fortransmitting uplink data to the base station, wherein the downlinkcontrol information comprises: a demodulation reference signal (DMRS)cyclic shift index field having a predetermined length, and modulationand coding scheme (MCS) information for each of the multiple data units;to receive, from the UE, the multiple data units with multiple DMRSstransmitted from the multiple transmission antennas, wherein each of themultiple DMRSs is cyclic shifted with different cyclic shift values, andwherein each value of the DMRS cyclic shift index field indicates acombination of different cyclic shift values for each of the multipleDMRSs; and wherein the MCS information includes ‘n*s’ bit information,wherein the ‘n’ corresponds to a number of the multiple data units, andthe ‘s’ corresponds to a number of bits for indicating MCS informationfor one data unit.